These studies are directed towards obtained a basic understanding of the structure and function of the most predominant extracellular matrix protein of periodontal ligament, collagen. Detailed structural information will be obtained by qualifying the molecular distribution of the covalent intermolecular cross-links in the collagen fibrils using tissue from two different aged bovine animals. Cross-linked peptides will be isolated and quantified by chromatographic methods from tryptic digests of the NaB3H4- reduced tissue. The glycosylation of the cross-linking residues in the isolated peptides will be studied. The tissue's native collagen will also be subjected to incubation under stimulated physiological conditions to allow the tissue to "mature" and "age" so that they can form the mature cross-links. The molecular distribution of the newly formed mature cross-links will be quantified in the same manner as above. Periodontal ligament is specifically an excellent model of these types of study. This is because the collagen molecules of this tissue are fully cross-linked by immature cross-links and mature cross-links are absent. This most probably is due to the tissue's exceptionally high rate for turnover. Based on the data from these experiments we can obtain information concerning the three dimensional structure of collagen fibrils of the periodontal ligament as well as the mechanisms involved in stabilization and maturation of the molecules in fibrillar collagenous matrices. Deglycosylated periodontal ligament collagens will also be subjected to in vitro incubation and structural changes will be studied in the same manner to explore the functional role of the glycosylation of specific Hyl residues in collagen in mature cross-link formation. This will provide insight into the role of the glycosylated cross- links in turnover of collagen in the body. All these data will be compared to other functionally different collagenous tissues of the body. In this manner, we can related structural and biochemical data to the unique functional role of periodontal ligament in an organism.